How is Creo 4 transition going?

I have Creo 4 installed and have looked at a few things but haven't yet been brave enough to lose reverting back to Creo 3 if things have gone south.

For those brave enough to dive in how is the experience going?  Have you ran into any crippling bugs?

From what I've seen so far it is looking somewhat promising.  I like some of the changes in the sketcher and I like the ability to extrude starting from somewhere besides the starting plane.